Numerical simulation of flow past an 8:1 oscillating rectangular cylinder at Re=22000

Abstract

Abstract To investigate the influence of structure’s oscillatory motion on flow, the present study employs the arbitrary Lagrangian–Eulerian method in k – ω shear stress transport (SST) turbulence model to simulate the flow past an oscillating rectangular cylinder at Re = 22 000. The cylinder undergoes reciprocating sinusoidal motion at a specified frequency f e , and the frequency ratio fr (defined as the ratio of cylinder oscillation frequency f e to the stationary cylinder vortex shedding frequency f 0 ), ranges from 0 to 4. The results demonstrate that, in the synchronization region (0.8 ⩽ fr ⩽ 1.2), the drag coefficient shows the most notable variation and reaches its maxima at fr = 1.1 and the root mean square ( r.m.s. ) of the lift coefficient is proportional to the square of fr ( C l ′ = 1.08 ∗ f r 2 , R 2 = 0.99). Moreover, the present study compares the similarities and differences of vortex shedding morphology between stationary and oscillating cylinders. With the increase of fr , the wake vortex gradually transforms from a single-row arrangement on the wake centerline to a parallel double-row arrangement, with the main vortex modes in the wake region observed as ‘2S’, ‘P + S’, ‘2P’ and ‘C’. Furthermore, spectral analysis, including amplitude spectrum analysis and wavelet analysis, in addition to probability density function statistical methods, are employed to comprehensively understand the velocity characteristics of the wake region. The results indicate that the oscillation of the cylinder reduces the correlation of the wake velocity. Those are beneficial in understanding the interaction between turbulence and structural fluid-induced motion.